Wind power is considered one of the cleanest, most environmentally friendly energy sources presently available, and wind turbines have gained increased attention in this regard. A modern wind turbine typically includes a tower, generator, gearbox, nacelle, and one or more rotor blades. The rotor blades capture kinetic energy of wind using known foil principles. The rotor blades transmit the kinetic energy in the form of rotational energy so as to turn a shaft coupling the rotor blades to a gear system, or if a gear system is not used, directly to the generator. The generator then converts the mechanical energy to electrical energy that may be deployed to a utility grid.
Typically, planetary gear systems are utilized in wind turbines, although parallel shaft gear systems and other suitable gear systems have also been utilized. Further, appropriate bearings must be selected and utilized for such gear systems due to the significant loading that the gear system experiences during operation of the wind turbine.
One example of a bearing that would be useful for reacting such relatively high loads is a journal bearing. However, during periods of low loading, or during start and stop cycles for the wind turbine, the journal bearings are generally exposed to high wear conditions, which can damage or destroy the journal bearings. Because such periods and cycles are frequent during the operation of a wind turbine, journal bearings are thus typically not utilized despite their high load reacting capabilities.
Thus, typical gear systems for wind turbines currently utilize roller bearings. However, roller bearings are relatively expensive components, and significantly increase the overall costs of the gear system.
Accordingly, an improved gear system is desired in the art. For example, a gear system that can react high loads and that is relatively inexpensive would be advantageous.